Infection of duck embryo fibroblasts by Marek's disease herpesvirus (MDHV), strain GA, leads to the induction of a new DNA polymerase. Studies are proposed to purify MDHV (GA)-induced DNA polymerase to homogeneity and to examine its catalytic and structural properties. Studies are also proposed to search for protein factors which, in addition to MDHV (GA)-induced DNA polymerase, function as part of the machinery that synthesizes MDHV DNA. In order to extend our knowledge of the types of DNA polymerases induced by herpesviruses, the catalytic and structural properties of the DNA polymerases induced by strains JM and BC-1 of MDHV and that induced by the herpesvirus of turkeys will be examined. The results of preliminary experiments indicate that the DNA polymerases induced by the JM and BC-1 strains of MDHV have some different properties from that induced by the GA strain. Finally, using the standard DNA polymerase enzymatic activity assay and a radioimmunoassay, the presence of MDHV-induced DNA polymerase in lymphoid tumor cells and in a continuous cell line will be assessed. This information might help to decide whether or not the viral-induced DNA polymerase is needed to replicate the resident viral genomes of these cell types.